Frame renforcement

[wallooner]

I have a 1977 Sovereign in great condition. It is a center bath model with no current frame issues. The running gear is well maintained and I intend to keep a close eye on it. I am planning extensive travel this winter and would like to take all reasonable preventive maintanence steps now. My unit has the 4 inch frame and of course is 31 ft long. I don't think I am going to be happy unless I have done something to renforcement the frame at least at its weakest point which I understand is just behind the rear axle. This is for my piece of mind. My thought was to double up the entire area exposed in the wheel wells. Maybe a piece of 12 gauge sheet metal bent to a 90 degree angle away from the frame at the top and cut out for the axles. Laying flat against the exposed frame and axle attatchment plate. Probably be about 8 inches wide with a inch or inch and a half bend at the 90 bend. It would then be bottled on. Somewhere in this forum I saw a similar plate maybe maufactured by someone. Does anyone have any issues with what I propose? Am I missing anything or does anyone have a better idea for a do-it-youselfer? I would rather m not weld because of the heat involved. Thankyou for your input.

[Bubba L]

I know that bolted stiffener plates work in steel construction but that's much heavier steel. Not sure how well bolts would work on such light gauge metal. On our 55, I cut a 4" x 4'-0" x 1/4" steel plate. I drilled 1/2" in holes and puddle welded where the holes were. I extended fore and aft of the axle to spread the load. I know you don't want the heat from welding, but that may be the most effective. Good luck.

[uncle_bob]

Hi

Unless your frame is rotted out, the strength of sheet metal is zip compared to what's in the frame. Double up the frame members (even without welding ) before you play with sheet metal.

Bob

[HiJoeSilver]

Check out this thread. Andy from Inland rv is a pro.

http://www.airforums.com/forums/f36/...ion-57888.html

I think you'd get more bang by replacing the axles if the ones on the trailer are original. Helps soften the tide if the old ones are stiff and shot.

[wallooner]

Thanks Bob, Are you saying use another 4 inch c channel and box it ?

[uncle_bob]

Originally Posted by wallooner

Thanks Bob, Are you saying use another 4 inch c channel and box it ?

Hi

I believe that would be stronger. You need to cary the load not just at the axles, but a ways away from them to really do much good. Welding will work better than bolts.

Bob

[Burnside Bob]

Dear Wallooner:

I don't want to sound argumentative but I'm not sure some of the suggestions addressing your problem are the best way to proceed. You, and the folks making these suggestions, are welcome to PM if you have any questions.

In general:

Airstream employs monocoque construction. The interior and exterior shells carry significant load. The shell is much more rigid than the frame, which is one reason the dreaded rear end separation occurs. For a brief discussion of the frame versus unibody versus monocoque methods of vehicle design, please see:

https://www.quora.com/What-is-the-di...-frame-in-cars


I would also suggest not adding any frame stiffeners to your Airstream, especially by welding. There is always flex in your trailer frame, and creating points in the frame where rigidity changes over a very short distance is a recipe for failure at that point, especially when the stiffener is welded in.

Welding changes the characteristics of steel making it more brittle. Yes there are techniques for reducing this effect, but they can't be employed on a completed trailer. Metal structures subject to flex and vibration typically are riveted or bolted, not welded.

Andy's comments in the referenced thread are spot on IMOP and I would follow his suggestions.

[rugjenkins]

I boxed my whole frame![emoji33] stiffing the frame will be ok. These frames are too thin, imho. Remember your airstream is 40 yrs old and has survived without mods to the frame. Personally strengthening the weak part of the is frame will be fine. Technically these trailer are semi-monocoque. I actually added a 1.5 perimeter band and bolted the shell to that. My floor can be removed anytime without doing a full Monty. The point is, these trailers can be modified or re-engineered to make them better. Have fun and enjoy the process. [emoji1]

[wallooner]

Thankyou for your reply I must admit I am now more confused than ever as Bob seemed to say reinforcing the frame might be counterproductive. I wonder why they eventually switched yto a 5 inch frame which of course would be stiffer. Also Airstream did produce a reinforcement plate for the 4. Inch frame. Did they warn about making the frame too stiff or was that item to repair a frame that already was cracked.My 31 footer has no issues at the moment I was just trying to prevent a frame related problem in the future considering it's age. Would you have any photos of your modification concerning the band attatchment to the exterior or maybe a more detailed explanation. Thankyou

[uncle_bob]

Hi

The pont being made is correct. It's not a simple problem. Adding a lot of structure in a small area just "moves" the flex point to the edge of that area. If you are going to change the frame, you need to do it over a fairly large area.

Bob

[wallooner]

Thankd

[wallooner]

Thanks Uncle Bob, Your causing me to rethink my plans to reinforce the frame. Maybe I should leave well enough alone and just make sure my axles and running gear are in good order which they are according to all the tests I have done. I will also refrain form loading anything heavy rear of the axles.

[uncle_bob]

Originally Posted by wallooner

Thanks Uncle Bob, Your causing me to rethink my plans to reinforce the frame. Maybe I should leave well enough alone and just make sure my axles and running gear are in good order which they are according to all the tests I have done. I will also refrain form loading anything heavy rear of the axles.

Hi

Keeping weight out of the rear of the trailer is a really good idea for a number of reasons .....

Bob

[Burnside Bob]

Originally Posted by wallooner

Thankyou for your reply I must admit I am now more confused than ever as Bob seemed to say reinforcing the frame might be counterproductive. I wonder why they eventually switched yto a 5 inch frame which of course would be stiffer. Also Airstream did produce a reinforcement plate for the 4. Inch frame. Did they warn about making the frame too stiff or was that item to repair a frame that already was cracked.My 31 footer has no issues at the moment I was just trying to prevent a frame related problem in the future considering it's age. Would you have any photos of your modification concerning the band attatchment to the exterior or maybe a more detailed explanation. Thankyou

We all bring different experiences and backgrounds to the discussion. Personally, I ran a custom fab shop for 10 years and prior to that did all the repair work on a larger farming operation, during which I saw quite a few frame failures on agricultural equipment. That said, I never worked on Airstreams (other than my own), which is why the thread in which Andy Roginski, owner of Inland RV, suggests NOT stiffening the frame, is important. He has worked on hundreds if not thousands of Airstreams and you can bet that anything his shop didn't do right came back to haunt him. It should also be noted that contemporary Airstreams have more goodies in them, consequently weigh more which requires a heavier frame. And I'm not arguing that the frame in your trailer was really, truly adequate.

The Andy Roginski thread is here: http://www.airforums.com/forums/f36/...ion-57888.html


Folks like Rugjenkins who have both skills and access to equipment can do marvellous things. And if you have both skills and equipment, why not do something special and make that baby yours! Real pride of ownership.

But from what you say, you weren't looking at a major reno--just prevention of a common failure. So I'd give Inland RV a call and see what they have to say. They've been there and done that so are well qualified to advise you.

[wallooner]

Thanks for your input. I will call Andy as you suggest. I just hope he is not fed up with talking about this issue.

[rugjenkins]

Sometimes the best answer is: "if ain't broke don't fix it." Remember your airstream and thousands more are the same way they came from the factory and have lasted 30, 40 years. Sometimes overthinking things confuse us. In your situation I'd leave it alone and invest in new axles. It is better to camp than reengineer. [emoji106][emoji1]